(1) Field of the Invention
The present invention relates to a bridge for data transfer between a USB 3 interface of a host device and a data storage device having an interface in accordance with a data storage standard. The invention is concerned with improving the data transfer rate between the host device and multiple data storage devices.
(2) Description of Related Art
A storage device such as a hard disk drive is typically provided with a standard interface, for example a Parallel Advanced Technology Attachment (PATA) interface, a Serial Advanced Technology Attachment (SATA) interface, or a Small Computer System Interface (SCSI). The standard interface comprises a standard physical interface designed for connecting to a corresponding standard physical interface within a host computer. Controller electronics may be located, for example, on the motherboard or as an additional plug-in adapter.
In such an arrangement, in which the standard physical interface of a storage device is connected to a corresponding standard physical interface within a host computer, the host computer communicates with the storage device via the physical interface using a protocol for commands to transfer data and status information between the host and the storage device.
In the case of PATA and SATA, the standards defining the protocol are ATA/ATAPI standards, which are available from ANSI or techstreet, as listed at the website address: http://www.incits.org/list_INCITS.htm. Relevant standards include: INCITS 361: 2002 (Information Technology—AT Attachment with Packet Interface—6, ATA/ATAPI-6); INCITS 317: 1998 [R2008] (AT Attachment+Packet Interface, ATA/ATAPI-4) [T13 ]; and INCITS 317: 1998 Erratum 1: 1999[ ] (Erratum to INCITS 317: 1998, AT Attachment+Packet Interface, ATA/ATAPI-4) [T13].
For SCSI, the relevant standards are available from the ANSI or INCITS standards store, as listed at the website address: http://www.t10.org/pubs.htm. Relevant standards include: Reduced Block Commands (RBC) (INCITS 330-2000 [R2006]); Reduced Block Commands (RBC) Amendment 1 (INCITS 330-2000/AM1-2003); SCSI Block Commands—2 (SBC-2) (INCITS 405-2005); and SCSI Primary Commands—3 (SPC-3) (INCITS 408-2005).
However, in order to connect a storage device (such as a PATA or SATA standard disk drive) to a host computer with the drive located external to the host computer, an alternative interface has traditionally been used. A reason for this is that, until the eSATA specification was introduced in 2004, no practical means existed to extend the physical PATA or SATA cabling beyond the confines of the host enclosure. The choice of alternative interfaces includes those defined by the IEEE 1394 or Universal Serial Bus (USB) standards. Interfaces defined by both of these standards are typically universally available on host computers. The present invention concerns, in particular, the use of interfaces defined by the USB standard (which may be simply referred to as USB interfaces).
The USB standards are freely available. For example, they may be obtained from the website address http://www.usb.org. The USB 2 standard is available in the Universal Serial Bus Standards revision 2.0, Apr. 27, 2000, which can be found at http://www.usb.org/developers/docs. The USB 3 (including USB 3.0) standard is available as Universal Serial Bus 3.0 Specification, revision 1.0, Nov. 12 2008, which can also be found at http://www.usb.org/developers/docs.
In order to connect a USB interface of a host computer with a different interface of a storage device, a bridge device is required. This is because the physical layer technology (including the physical interfaces) and higher layer protocol standards are different between the USB protocol and the protocol used by the mass storage device. The PATA and/or SATA standard may be used herein to represent the protocol used by the mass storage device, but it will be understood that the mass storage device could use any other suitable protocol.
The bridge device must be capable of acting as a bridge between the USB interface (which includes a physical port) of the host computer and the PATA or SATA interface (which also includes a physical port) of the storage device. Thus the bridge must provide a USB interface for connecting to the USB interface on the host computer and also a PATA or SATA interface for connecting to the PATA or SATA interface of the storage device. The bridge is configured to translate the protocols used to carry the commands and data between the USB host and the bridge (i.e. the USB protocol defined by the USB standard), and between the bridge and the storage device (eg the PATA/SATA protocol defined by the ATA/ATAPI-6 standard).
One aspect of the present invention relates to providing a bridge between a USB 3 interface and multiple downstream data storage interfaces.
Another aspect of the present invention relates to providing a bridge between a USB 3 interface and multiple downstream data storage interfaces, at least one of which is a USB 3 interface.